lavc/qsvenc: allow to set qp range for h264 BRC

Signed-off-by: Zhong Li <zhong.li@intel.com>
Signed-off-by: Maxym Dmytrychenko <maxim.d33@gmail.com>

libavcodec/qsvenc.c

@@ -665,6 +665,20 @@ FF_ENABLE_DEPRECATION_WARNINGS
                 q->extco2.AdaptiveB = q->adaptive_b ? MFX_CODINGOPTION_ON : MFX_CODINGOPTION_OFF;
 #endif
 
+#if QSV_VERSION_ATLEAST(1, 9)
+            if (avctx->qmin >= 0 && avctx->qmax >= 0 && avctx->qmin > avctx->qmax) {
+                av_log(avctx, AV_LOG_ERROR, "qmin and or qmax are set but invalid, please make sure min <= max\n");
+                return AVERROR(EINVAL);
+            }
+            if (avctx->qmin >= 0) {
+                q->extco2.MinQPI = avctx->qmin > 51 ? 51 : avctx->qmin;
+                q->extco2.MinQPP = q->extco2.MinQPB = q->extco2.MinQPI;
+            }
+            if (avctx->qmax >= 0) {
+                q->extco2.MaxQPI = avctx->qmax > 51 ? 51 : avctx->qmax;
+                q->extco2.MaxQPP = q->extco2.MaxQPB = q->extco2.MaxQPI;
+            }
+#endif
             q->extparam_internal[q->nb_extparam_internal++] = (mfxExtBuffer *)&q->extco2;
         }
 #endif

libavcodec/qsvenc_h264.c

@@ -118,6 +118,8 @@ static const AVCodecDefault qsv_enc_defaults[] = {
     // same as the x264 default
     { "g",         "250"   },
     { "bf",        "3"     },
+    { "qmin",      "-1"    },
+    { "qmax",      "-1"    },
 #if FF_API_CODER_TYPE
     { "coder",     "-1"    },
 #endif